Inkjet printers fire drops of ink from the nozzles in a printhead of an ink pen on to paper or other print media. Ink pens are sometimes also referred to as print cartridges or ink cartridges. In many types of inkjet printers, several ink pens are mounted on a movable carriage that traverses back and forth across the width of the paper feeding through the printer. Each ink pen dispenses one or sometimes two different colored inks. The pressure in each ink pen is managed to help control the flow of ink to the printhead. For example, if the ink pen lacks sufficient to back pressure, ink may leak from the printhead nozzles. Alternatively, if the back pressure in the ink pen is excessive, the printhead may not fire properly. However, even with effective back pressure management, the printhead may lose its prime due to the accumulation of air bubbles or other gases in the printhead, limiting the ability of the printhead to properly receive or dispense ink. Also, nozzles sometimes become clogged. Thus, it is sometimes necessary to push ink through the printhead, or pull ink from the printhead, to clear clogged nozzles and/or to re-prime the printhead.
To push ink through the printhead to clear clogged nozzles and/or to prime the printhead, air is pumped into a pressure regulator chamber in the ink pen to push ink out through the nozzles along with any gas bubbles that may have been trapped in the printhead. Pushing ink out of the nozzles in this manner is referred to as “pressure priming”, “push priming” or “pressure purging.” Conventional pressure priming systems either have not been adapted for use with a movable carriage or they have not been contained on-board the carriage. Where the pump is remote from the carriage, the air connection between the pump and the ink pens on-board the carriage must be made and then broken each time a purge/prime is conducted.